Hurricane Irene: A significant threat to the U.S. East Coast

It’s time for the U.S. East Coast, from Florida to the Carolinas to New England, to take Hurricane Irene seriously.

Irene has continued to organize this afternoon, and as the following NOAA image shows it was already a large system earlier today.

Irene, earlier today, north of Puerto Rico. (NOAA)

Forecasters have steadily upped their intensity estimates for Irene (now expected to be a major hurricane with 115-mph winds in five days) because it has followed a more northerly track than expected, keeping its center largely offshore.

The system is now not expected to be substantially affected by Hispaniola or Cuba.

This means Irene will have a largely unchecked path toward the east coast. Here’s a look at some of the latest track models runs, which continue to favor a landfall along the Carolinas or points northward.

Hurricane Irene 12z track models. (NCAR)

The National Hurricane Center’s official forecast is consistent with these models, bringing a major hurricane toward the Carolinas or Virginia by Saturday morning.

On the current track, assuming Irene’s center remains to the north of Hispaniola, the system could become the most intense hurricane to strike the U.S. East Coast since 1989’s Hurricane Hugo. That assumes it does indeed come ashore and not bend more strongly to the northeast, remaining over the Atlantic.

Named storms that have passed just to the north of Puerto Rico and gone on to strike the United States, including Hugo, have typically been very damaging.

A search using the iCat Damage Estimator finds seven named storms passing within 50 miles of Irene’s present position on the hurricane record, causing an average of $11.9 billion in damages (present-day dollars).

It’s far from clear where Irene will ultimately go, because there’s considerable error in four- and five-day tracks.

But what is clear at this point is that the system is a significant threat to the United States, and there’s no reason to be confident it will be like Hurricane Earl last year, which menaced the coast but remained offshore.

In fact the greater likelihood is a serious hurricane striking the East Coast this weekend.